Any Hard Data On Silver Quantity?

[paul ron]

I was a clinical chemist once upon a long time ago, so looking at this problem of quantification is a simple one, especially if you want to calculate it on paper. BTW I worked in the lab for 16 years using only a slide rule for my calculations before I bought the one of the first Bomar Brains to hit the streets.

All your densitometry measurements are nothing more than Voodo at best, slide rules and all. The only way to know exactly how much pure silver is in any emulsion is do an actual extraction of the silver itself... right off the undeveloped film or paper.

So what was the original question again?

""I'm about to experiment further with film, paper, and fixer.
Is there any solid information, whatever the source, on the
quantity of silver in the gelatins of film and paper? Dan"" as quoted from the APUG thread.

And where does all this desitometry nonsense come into this conversation again? So you can cerebralize this all you want, but you missed the point. OTOH I'm impressed as all hell with the amount of information in this conversation.

 

[rjr]

Ed,

That is US$ 0.05 per roll, and at the rate of 100 rolls a year, that indicates a grand total of $5.00. How much does a small Silver Recovery System cost, and what value can we project for the labor involved, and the expenses incidental to the process as a whole - to the point where our proceeds can be deposited in our bank account?

Now, thats an easy question.

It costs me 5EUR worth of Sodium Dithionite - thats good enough for 500g of that stuff (probably cheaper in larger bulk) which is able to recover silver at a rate of ca. 0,8g Sodium Dithionite per 1g Silver.

One or two teaspoons per liter of spent fixer, agitate it a bit and leave it outside for a week or so. SO2 will form and evaporate (so leave the tank open!) and the silver will fall out as a black sludge of colloid silver and silver sulfide. Pour off the excessive liquid and filter the rest, dry the cake and collect it for further processing.

Re your bank account - it won´t be much. No one will take such a small account anymore, silver is dirt-cheap if compared to the early 1980s. So I (and many others I know) keep the stuff, I´ll melt it one day when I have enough in the can to justify the work.

Sodium Dithionite works as a chemical foggant (and is applied in bw slide processing! Anyone should have it in his darkroom DIY chemistry kit , so don´t do this in your darkroom.

You also - I don't want to use the term "demand"... let's say "challenge" us 100-rolls-a-year lab operators to PROVE that our dumping of silver (and I would assume other chemical compounds) do not "harm the environment." If you remember, I was also seeking information about toxicity - without that I can't reasonably form an opinion either way - nor will I argue the question.

Silver has a quite strong antibacterial function (and funghizide...), it is used to treat and desinfect potable water (you can buy it for your trekking trip in form of a powder. "Micropur" is one of the brand desinfectants involving silver) and even used in wound care (http://www.us.coloplast.com/ECompan...d59af4143fe4b4a085256cc500531f3b?OpenDocument).

There is no reason to spoil the sewage facility for this minute amount of cost and work involved, so I don´t do it. Period.

 

[dancqu]

And where does all this desitometry
nonsense come into this conversation again?

Don't look at me. I've indicated that I'd use a thiosulfate
extraction. It's the steps following that which I'm now
considering.

I'm not positive from whom densitometry entered upon
this conversation. Dan

 

[Ed Sukach]

.
There is no reason to spoil the sewage facility for this minute amount of cost and work involved, so I don´t do it. Period.

Again, I have information that would indicate to me that my darkroom discharge would have such a slight effect on the sewage system as to be of NO concern - this is from a hyper-sensitive organization that is the prime enforcer of the Rules.
A good friend of mine (haven't seen him for a month or two) is in charge of the local Waste Water Treatment Facility. I can get information of the volume of water treated - I don't remember that offhand, but I think it was easily in the hundreds of millions of gallons per year. Sewerage is treated chemically and mechanically (sludge separation, aeration) and fungicides and bactericides are used regularly - so I would think that silver would add - though micro-microscopically - to the effort.

By the way ... Any idea of how much "Black Sludge Silver" you have?

Come to think of it ... wouldn't the release of Sulphur Dioxide add to air pollution and acid rain?

As I've said. I really need information on quantity and toxicity to form some rational opinion.

 

[Kirk Keyes]

The point is, diluted 1:4 or 1:9 the capacity per liter is the same.
Do a little arithmatic. From Helen B's post take 1.6 grams/meter
square silver. Assume half ends up in the fix. Ilfords maximum
for archival results is .5 gram per liter. An 8x10 is 1/20 of
a square meter. How many 8x10s can be fixed? Dan

Dan - you don't need to do any arithmetic to find out how many 8x10s can be fixed. Go to Ilford's web site, and for both Ilfotec II and Hypam fixers, they state a capacity of 40 8x10 sheets (2 sq. m.) for fiber and 80 8x10 sheets (4 sq. m.).

Maybe you want to work backwards from those number and figure out what the concentration of silver is per unit volume, i.e. ml, of the original fixer solution? You will find that you will have two different concentrations depending on which initial fixer dilution you start with.

Kirk - www.keyesphoto.com

 

[Kirk Keyes]

We have been talking back and forth comparing apples and oranges. There are certain facts that are as true now as they were in the days of Hurter & Driffield. [...] They proved that in any given colloidal silver suspension, the optical density is proportional to the mass of silver per unit area. This finding allowed the use of the familiar characteristic curve to analyze developer performance by maesurement of optical density, which is very much easier than the quantitative analysis of silver content. They also knew that maximum density was not correlated to silver content of the undeveloped emulsion alone.

We in our brilliance redicover many things. I don't know how many of you have access to the Hurter and Driffield Memorial Volume, but if you can find one it will be very interesting reading. Mine was given to me by a friend.

Well Patrick - that's fine, but you still do not seem to be taking into account that different emulsion/developers will give a different optical density for a given amount of silver.

I've got that book as well - I think I found it on the net for about $15.

 

[gainer]

Kirk said: "Well Patrick - that's fine, but you still do not seem to be taking into account that different emulsion/developers will give a different optical density for a given amount of silver. "

For practical photography, that is exactly why we use the characteristic curve and find it different for different combinations of film and developer. It was the genius of H&D to show that it would not be necessary to measure the amount of silver. Whatever we need to make photographs we can get by measuring optical densities.

If, for some reason of basic research, you must know how much silver is in an emulsion initially and/or how much is contained in the images on a particular strip of film, then certainly quantitative chemical analysis is the way to do it. Few of us have the necessary equipment to do that. If OTH you want an idea of how much silver you might recover from scrapped or used film, by the time you find out analytically, you have spent more money on the analysis than you could make by simply recovering the silver from hypo or blix. By your own statement, it will not do to measure one roll or sheet of film and do a slide rule and napkin estimate. You must recover the silver first and then calculate whether it was economical.

 

[Ed Sukach]

I've been thinking of this $1500 worth of silver every six months...

IF there IS $0.05 worth of silver recovered from each roll of film...

That would require recovering the silver from ... $1500 / $0.05 = 30,000 (thirty thousand) rolls of film (neglecting paper development- as I have *no* idea - not even hearsay - of the silver involved there) per every six month period.

Given 300 days of operation per year, at twelve hours a day - using my Hasselblads (120 film, 12 exposure/per roll) that works out to ... 200 rolls/ day ... and therefore ... 200 exposures per hour.

Sounds like a rather LARGE studio to me.

 

[Aggie]

Hi Ed
re: your doubt of my figure of $1500 for 6 month period

The 6 month period included all film processed, contacted , all fibre fix, all ciba bleach fix, all ra4 bleach fix.
We as well accept used fix from darkroom users that know we recover chemicals.
To be fair we process thousands of rolls , sheets of film a year, and I print daily with a fairly heavy show,portfolio clientelle.
But , to my point we are a very small shop compared to the Large Photo Labs and if we can save this type of silver every 6 months think of the amount of silver going down the drain if it is not being recovered.( how many home darkrooms are capturing their chemistrys?)
I would hope every one on this forum is recovering their used chemicals.

A recent poll on this forum indicated to me that there are a lot of talented indivuduals with heavy chemistry background, I totally defer to them on this issue. But until someone can prove to me and actually the Toronto Chemical Waste group that dumping photo chemistrys down the drain is ok for the enviornment , I will continue to reclaim my fix. As well get money for this practice.

Yeah I have a BIG problem with this asertion. On the spot market close for silver on Friday, the high was in the world, $6.90 per ounce. You would have had to at that all time high had to produce over 13 pounds of pure refined silver to have your $1500 recover total. When silver gets sent off to be reprocessed, it is done by how much waste is invovled with the reprocessing. Pure bench (talking as a jeweler)Ie cut off bits and other large chunks, and such that have no other contamination in it will gain you about 80% recovery value of what ever precious material you send in. If you happen to get gold in with your silver the cost goes down, since they have to go through another step to process out the other metal. Next level is the bench sweeps where you taking the filings, and shavings of the metal you were working on. This will get you about a 65% value. Lastly is floor sweeps, filters and other such trapping devises. That you get about 25% value. Now the value is based on the actual weight of the metals recovered after processing, not the weight of the item you send in as in a filter that traps the metal. When I worked for a high end jeweler, his silver never came near that total. He had mostly the first two types of recovery. His processing of silver directly in fabrication of jewelry would be far greater than the minute amounts of silver used in processing of film and paper. His checks for silver would earn him less than $100 in a 3 month period. He employed 4 bench jewelers. He also dealt direct with the metal vendors such as Hauser and Miller, and Rio Grande.

Even the black sludge that Roman talks about will need to be smelted down, and impurities removed.

 

[dancqu]

Go to Ilford's web site, and for both Ilfotec
II and Hypam fixers, they state a capacity of 40 8x10 sheets
(2 sq. m.) for fiber and 80 8x10 sheets (4 sq. m.) for RC.

You will find that you will have two different concentrations
depending on which initial fixer dilution you start with.

Within certain bounds it does not matter what dilution is used.
The Ilford maximum for archival results is .5 grams silver PER
LITER, whatever the dilution, sodium or ammonium.
Grant Haist does not distinguish twixt the two.

Two put it bluntly, If you used a liter of concentrate as a
working strength solution, the maximum silver concentration will
remain .5 grams silver for that liter of concentrate.

In other words, you can not put more prints through one liter
of 1:4 dilution than you can through one liter of 1:9 dilution.

It used to puzzle me that G. Haist never mentioned dilution
or sodium or ammonium. He only mentioned silver PER UNIT
volume. I even asked the question on rec.photo.darkroom, liter of
what? and how much? But it finally dawned. Dan

 

[rjr]

Aggie,

"Even the black sludge that Roman talks about will need to be smelted down, and impurities removed."

Yep - there is lots of sulphur in there, both in form of pure "sulphur flakes" and as silver sulfide. But you could process it at home, on a kitchen table. ;-)

 

[Jorge]

I have tried sloughing thorugh this thread, and as interesting as the responses are, I am still not sure why the questions was asked and about some of the answers.

So here is my take. If you want to know the amount of silver for Maximum black on papers, it does not matter. There is no correlation between amount of silver and how black a paper can look.

If you want to know the amount of silver for environmental concerns, just drop a steel mesh in the fixer and you will have removed most of it out of the fixer.

If you want to know the amount of silver so that you can make your fixer work till the last drop, this is being penny wise and pound foolish. Just follow the manufacturer directions and you will be fine, trying to save a few pennies by using the fixer to saturation and then risking having a valuable negative ruined or print that you have sold turning yellow or dissapearing is foolish IMO.

Having said all this, if my life depended on finding out how much silver is on a piece of film at home, I would simply soak the film in household bleach until the emulsion has dissolved in it, add some rock salt and weight the amount of resulting silver chloride, you can then easily calculate the concentration of silver. No need to use all these complicated methods.

 

[Kirk Keyes]

Jorge - thanks for the summation!

"I would simply soak the film in household bleach until the emulsion has dissolved in it, add some rock salt and weight the amount of resulting silver chloride, you can then easily calculate the concentration of silver."

Have you tried this? I suspect that the silver will already be precipitated as a choride from the bleach, so you would then have to wash away the remaining material, which hopefully is soluble or use a furnace to burn it off after washing away whatever is soluble at that point...

One will still need a 4 place balance to make accurate measurement, unless you want to use a lot of material to start with! May not be so bad for paper, but it could get expensive for films.

Kirk - www.keyesphoto.com

 

[Jorge]

Jorge - thanks for the summation!

"I would simply soak the film in household bleach until the emulsion has dissolved in it, add some rock salt and weight the amount of resulting silver chloride, you can then easily calculate the concentration of silver."

Have you tried this? I suspect that the silver will already be precipitated as a choride from the bleach, so you would then have to wash away the remaining material, which hopefully is soluble or use a furnace to burn it off after washing away whatever is soluble at that point...

One will still need a 4 place balance to make accurate measurement, unless you want to use a lot of material to start with! May not be so bad for paper, but it could get expensive for films.

Kirk - www.keyesphoto.com

I have done this but with developed film. The addition of salt would be an extra step just for completion.

As to the four place balance and the furnace, why? I have a little RCBS that reads up to 100 th of a gram, good enough. just weight some filter paper, filter the bleach solution and you have a pretty good indication of the amount of silver.

Remember folks, when you hear the sounds of hooves, think horses, not zebras....At least in the American continent..

 

[Bob Carnie]

Hi Ed,Aggie

don't take this response as combative as it is not intended to be.

We had a spot inspection at our facility earlier this year, The Municipal Toronto Environment group.
Mid day two guys showed up with a series of bottles and basically ordered us to turn on our silver recovery unit and they sampled the fluids that came out of this unit at the floor drain.
As I stated earlier we passed this test and I could fax you the results if you send me a email, or If I can figure out how to do an attachment to this post I will do so. Further conversations with this group confirmed that if we did not pass this test our operation would have to put in a proper unit or be shut down , Anyone with a wet darkroom was on their list to check without notice.
As well we are not allowed to put our used selinium in this machine , we keep it seperate in very large containers for future disposal.
At present there is 460hours of operation on the machine, and the cartridges will be changed at 600 hours. This changing of the cartridges happens every 6-9months.
I cannot tell you exactly how many films , paper , bleach fix goes through this unit every year. The old machine we had would clump the sludge around a cylinder and we would keep the sludge and indeed I recieved a cheque for $1500 for this sludge( I bought this unit for $1000 used).
The unit we use now is made or produced by Environmental Control Systems,
www.ecs-cares.com they are located in Barrie Ont.
They may be able to explain the value of captured silver as they installed, do visual spot checks to make sure the machine is working and take the cartridges away for the captured silver. This is all at no charge to me as it is their machine, I again think it is a lot of work for these people for no percieved financial value.
Every single darkroom I have ever worked in mine and others had a silver recovery unit at the back end of the drainage system leaving the occupied spaces or captured the fix. I am going back to 1976, I do not recall if the college I went to had one for their darkrooms.

If APUGers darkrooms were all here in Toronto there would be no dumping of the chemistry down the drain without a proper recovery unit. That is the law here. As stated before, these system"s seem to work well and I do recieve large volumes of chemistrys from various artists in my area. Therefore the higher possible returns financially.

 

[Kirk Keyes]

If APUGers darkrooms were all here in Toronto there would be no dumping of the chemistry down the drain without a proper recovery unit. That is the law here.

I highly suspect that this "law" only applies to commercial operations. US Federal law does not require this of home hobbists and I suspect that may be the case in Canada as well, but since I know nothing about Canadian Environmental law, its best to look to someone that know more than I...

 

[Bob Carnie]

Hi Kirk

Actually , here in Toronto this "law " applies to any wet darkroom, school, art co-op, commercial lab, small lab, home hobbiest. Because my lab is operating commercially , we were one of the first to be checked out. But I know that all wet darkrooms fell into the citys mandate, large or small.
A lot of my clients print themselves at home and do bring there chemistrys to dump.Very few have been checked as the commercial labs are first on the hit list.

 

[Ed Sukach]

Hi Ed,Aggie

don't take this response as combative as it is not intended to be.

We had a spot inspection at our facility earlier this year, The Municipal Toronto Environment group..

I do not desire combat, either.

My concern was not about whether I was in compliance with the law or not - I know I am. I was concerned with the actual effect of the silver/ chemistry effluent I was producing. I just do not have rational data I can apply to that determination.

Congratulations (??) on your compliance with the "law". Is that some sort of "city" ordinance - or does it affect those "out of town"?

You say you bought that Silver Recovery system for $1000. At my - guessed at - recovery value of $5.00/ year, and neglecting all other costs - in only 200 years *I* could expect to break even...

Be that as it may ... I would seriously consider that system if it, in truth, had anything near a significant beneficial impact on the environment.
That is what I am trying to find out.

If I go to my kitchen, and take a silver spoon, and proceed to throw it into the woods behind my house ....
Just how "nasty" is that silver spoon, anyway?

 

[gainer]

Considering that silver is one of the noble metals that do not easily dissolve, and that it is mined directly as metal from the ground in some places, I doubt that the silver itself is the concern. As it comes from our darkrooms, it is usually dissolved in the fixer, and in sufficient quantities may act as a bactericide against helpful bacteria. Just guessing.

 

[Kirk Keyes]

Considering that silver is one of the noble metals that do not easily dissolve, and that it is mined directly as metal from the ground in some places, I doubt that the silver itself is the concern. As it comes from our darkrooms, it is usually dissolved in the fixer, and in sufficient quantities may act as a bactericide against helpful bacteria. Just guessing.

I dn't know which acid you've been reacting your silver with, but I find it is readily attacked by hydrochloric and nitric acids. Remember that while silver is right above gold it is still right below copper which also reacts strongy with those acids - all are members of Group 11 (IB).

Silver is in the EPA 13 Priority Pollutant Metals list - so they are certainly concerned with it. It has been shown to have an adverse affect on wildlife and the environment.

 

[Ed Sukach]

Silver is in the EPA 13 Priority Pollutant Metals list - so they are certainly concerned with it. It has been shown to have an adverse affect on wildlife and the environment.

Aha! A possible light at the end of the tunnel.

What is this "EPA 13 Priority Pollutant Metals list"?. Where can I obtain a copy?

Any idea of the "adverse effects"??

 

[gainer]

I dn't know which acid you've been reacting your silver with, but I find it is readily attacked by hydrochloric and nitric acids. Remember that while silver is right above gold it is still right below copper which also reacts strongy with those acids - all are members of Group 11 (IB).

Sure, we learned that in freshman chemistry. That is why that mixture is called "aqua regia". How often do you encounter that potent reagent in nature outside of Pittsburg or L.A.? I can get HCl at the hardware store. Where do I get nitric acid? I still don't see how a silver spoon in my back yard would be attacked by anything but SO2 in the air or water here. The coating of silver sulfide protects it from further reaction. That is one reason for sulfide-sepia toning.

 

[gainer]

Furthermore, if it is so dangerous, maybe we SHOULD throw away our silver spoons.

 

[Aggie]

What ever happend to cloud sxeeding during drought times? Anyone remember the chemical used to seed those clouds with? It all rained or snowed down upon our heads. If memory serves me right it was SILVER NITRATE. It has not been disconntinued that I know of. Of course considering the weather around here the last couple of days, I think the rest of the USA won't have to worry about cloud seeding the rest of this winter.

I still have a problem and that was the gist of my previous post that you can recover $1500 worht of silver from processing film in just 6 months worth of time. I'm talking at todays prices of that being over 13 pounds of pure refined silver. Not the sludge that is a mixture of other things. 13 pounds if you take 13 boxes of margerine or butter and make a pile will give you the idea of the volume you would be dealing with. I have a tupperware box at my jewelry bench that has 2 pounds of silver in it right now. that box is 4 1/2 inches square. That is silver. I can take a picture and post it so you can see what the size of this is. 3/4 of that box is pure silver the rest sterling.

 

[rjr]

Silver disposal

Ed,

Why do you rely on the work of others to answer your questions? Many of this is answerable with a mediocre search machine? You got some answers, they don´t suit your predefined expectations. So?

Aha! A possible light at the end of the tunnel.

Have a look at

http://www.kodak.com/US/en/dpq/site/TKX/name/hseSilverManagement -

pretty much _everything_ is answered there, from small scale amateur use to large scale, high output commercial labs, from "Silver sources" to

Pretty much everything is said in:
http://www.kodak.com/global/en/corp/environment/kes/pubs/pdfs/J216.pdf

My position, again:

I can´t stand the smell of a rotting sewage plant and I don´t want to bath/drink/wash/row in contaminated water (I suffered an infection of Giardiasis from bad water in 2003, believe, it ain´t no fun), so I don´t dispose laquer, benzine, paint, acids or fixer in the sewage because that will affect the bacterias taking care of the excrements and I actually expect the same from others. As does the company running the plant and the local environmental department.

Re "scale" - there is no such thing in this regard. If you allow "minimal input" in a system, you´d have to control the timing of this input to split the "capacity" even between potential users.

You can´t, so´ll end up with a critical amount of hazardous material at one moment or the other and then the bacteriae in your sewage system will jump the shark due to a few seeing only themselves when looking in the mirror.